In order to be able to manufacture aluminium, manufacturers have to make available electrode mass to be used for electrodes in an aluminium melting bath in order to be able to produce aluminium from alumina (AlO2).
Petroleum coke or petrol coke is a carbonic solid material being a by-product or waste product from oil manufacturing, from coke making plants at oil refineries or a product resulting from other cracking processes. Petroleum coke is used for the manufacturing of silicon carbide.
Aluminium manufacturing plants are located at many places in the world. Petroleum coke being a substantial part of so-called electrode mass arrives by ship or train and is stored at in a large volume protected from weather conditions. Multiple plants for manufacturing of electrode mass are present in the world.
In order to optimize the manufacturing of aluminium, many attempts have been made to improve the quality of the electrode mass.
A drawback of the current manufacturing process of electrodes is that the electrode mass material they are made of, viz. petroleum coke and pitch, may have too low efficiency of adherence of added pitch due to large particles of the mass material having had insufficient nucleus temperature when pitch was applied. A further drawback being insufficient homogeneity in the mass material is also of great concern. These drawbacks, either separately or combined, may easily yield reduced electrode life, more use of electrode material than necessary at an aluminium production plant, more work involved due to more frequent replacement of electrodes, and above all increased cost in the overall manufacturing of aluminium due to a larger consumption of electrodes and increased maintenance cost. This in turn will inherently yield risk of complaints on product quality and observed products defects in operation.
Although heating and mixing operations of petroleum coke components and the added pitch are well known in many varieties in the prior art, it is nevertheless difficult to obtain a homogeneous mass material for making an electrode.
Insufficient homogeneity implies that conductivity at any selected location along an electrode is not the same, which is frequently caused by the coke components of varying size not mutually fitting in a proper manner and too much non-conductive, interconnecting pitch being present at some locations contrary to the amount of such pitch at other locations. Inherently, this has its origin in discharged electrode mass material having been insufficiently mixed/fluidized and with more pitch at some places in the discharged mass material mixture than at other places. To any expert in the art, this is a well known and at times also a rather problematic issue.
Further, prior art solutions have the drawback that the power consumption in making electrodes may become quite high, and not perfectly made electrodes may also add to the production cost of aluminium as regards power consumption if ohmic resistance at any location throughout the manufactured electrode is not consistent.